Field of the Disclosure
The following relates generally to wireless communication, and more specifically to techniques for protecting communications in a Wireless Local Area Network (WLAN).
Description of Related Art
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). WLANs, such as Wi-Fi (IEEE 802.11) networks are widely deployed and used. Other examples of such multiple-access systems may include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, and orthogonal frequency-division multiple access (OFDMA) systems.
Generally, a wireless multiple-access communications system may include a number of access points (APs), each simultaneously supporting communications for multiple mobile devices or stations (STAs), for example, in a particular WLAN. APs may communicate with STAs on downstream and upstream links. Each AP has a coverage range, which may be referred to as the coverage area of the cell. In a wireless local area network (WLAN), such as Wi-Fi, an AP may communicate with multiple STAs over a shared radio frequency spectrum. The STAs may use contention procedures, such as request to send/clear to send (RTS/CTS) messaging, to limit interference experienced by nearby communication devices. Contention procedures, such as RTS/CTS messaging, may in essence clear the communication path for a first device (e.g., a STA or AP) to transmit data to a second device. For example, prior to transmitting data to a second device, a STA, may first send a request to send (RTS) frame to the second device. The second device may respond to the RTS frame with a clear to send (CTS) frame clearing the STA to begin transmitting data to the second device.
Other devices may monitor the medium to determine if the channel is idle (e.g., using energy detection techniques). If a device determines that the channel is not idle (e.g., the energy level is above a threshold), the device may refrain from attempts to transmit for a pre-determined duration. In one example, a device may wait an extended interframe space interval (EIFS) before resuming attempts to transmit on the medium based on detecting the energy level of the channel is above the threshold. However, an EIFS may not be a sufficiently long duration to protect multi-user (MU) transmissions from multiple devices. Therefore, some devices may begin transmitting control or data frames that interfere with the MU transmissions. This may reduce the overall throughput and reliability of the wireless network.